VOL. XIX. (2) NOTES ON CH IRODOTA-SPICVLES 
117 
The number of the rays forming the central portions of 
the spicules varies in my examples from 6 to ii. In some 
examples the ray is flat or petaloid, and in some round, as 
described by Messrs. Terquem and Bertelin, although as 
between specimens from each locality the characters are for 
the most part constant. These characters may point to 
specific differences. Except in the case of the Lower Tuffley 
clay, where they appear to be quite abundant, the spicules 
occur very sparingly. 
